Strange turtle carving from either India or Singapore…

My boyfriend has had this little turtle carving for as long as we’ve been together (3+ years) and we have “fought” over the material this wee guy is made out of. He bought it on an trip, either in India or Singapore - he can’t remember. He is adamant it is some sort of bone carving. I think it’s a crystal/ mineral?? Possibly quartz that’s just been dyed black. We have done our googling and researching but to no avail. Could it also just be resin?

Other features worth noting:

It’s quite light, lighter than any other crystals of a similar size that I own, and it’s not cold to touch like other gem stones

The whole thing used to be the same black colour as the bottom but it has been bleached by the sun as it sits on a windowsill.

It used to be fairly glossy/ shiny before being bleached

It appears to be made of many thin layers as shown in pics

It does not float in water.

Many thanks in advance for your help! Would love to solve this mystery